The proposed three-year plan involves three goals: 1) collect daily diary data to examine links between biological indicators of stress, coping with interpersonal tensions, and daily psychological well-being, 2) continue research using existing data regarding stress and Cortisol, and 3) use the knowledge gained to write an ROl to examine biological indicators of stress, coping strategies, and implications for later well-being. The candidate's overall research goal is to identify links between biological indicators of stress, coping behaviors and daily psychological well-being. Interpersonal tensions are the most common and detrimental source of stress for well-being. People are most likely to use avoidance (e.g., do nothing) to cope with interpersonal problems and the use of avoidance increases with age, but there little research on the implications of daily avoidance. The proposed study assesses how people respond to daily tensions, whether responses vary by age, and associations among coping strategies, biological indicators of stress, and well-being. The daily diary project will include a regionally representative sample of 108 adults (aged 40 to 80+) from the Detroit Tri-County area. Participants will complete a baseline interview regarding social relationships and demographics, followed by daily phone interviews regarding tensions each night for 14 days. On days 6 through 9, participants will provide salivary samples four times a day (waking, 30 minutes after waking, before lunch, and bed time) as well as salivary samples after they experience interpersonal tensions. Samples will be analyzed for Cortisol, DHEA-S, and alpha-amylase. It is predicted that older people will report greater avoidance and that avoidance will be more highly associated with well-being (e.g., lower Cortisol, higher self-reported well-being) among older adults. It is also expected that certain types of avoidance are more beneficial (e.g., accepting the situation) than others (e.g., walking away) for well-being. These goals parallel the National Institutes on Aging missions to: 1) improve the health and quality of life of older people; and 2) understand the biological and psychological pathways through which social relationships may influence health.